The cohort of anti-HIV positive donors and controls has been under prospective follow-up since 1985. The original analysis of the study was published in the New England Journal of Medicine (321:917,1989). A reanalysis of the data, six years after study initiation is in progress. At enrollment, 182 subjects were western blot (WB) positive, including 158 asymptomatic donors, nine sexual partners of these donors and 15 persons HIV infected by blood transfusion. In addition, we enrolled a control population consisting of 70 donors who were anti-HIV reactive on the screening enzyme immunoassay (EIA), but WB negative or WB indeterminate (21). Of the 182 subject WB positive at enrollment, 43 (23.6%) have developed AIDS or ARC and 24 (13%) have died from an HIV related event. There has been no AIDS/ARC and no deaths in the control populations, including those that were WB indeterminate. Among the patients who expired, 17 were donors (10.7% of WB+ donors), 1 was a sexual partner (11.1% of partners) and 8 were blood recipients (53.3%) of recipients). We are in the process of analyzing whether the increased severity in blood recipients is a function of the time since exposure or of the presumed large viral burden at the time of transfusion. There are 117 patients in active follow-up of whom 106 were WB positive and 10 were WB indeterminate at enrollment. Among the 117 patients in active follow-up, 11 (9.4%) have AIDS/ARC.